Faculty Bibliography

OBJECTIVE:The goal of this study was to validate the Global Alignment and Proportion (GAP) score in a cohort of patients undergoing adult spinal deformity (ASD) surgery. The GAP score is a novel measure that uses sagittal parameters relative to each patient's lumbosacral anatomy to predict mechanical complications after ASD surgery. External validation is required. METHODS:Adult ASD patients undergoing > 4 levels of posterior fusion with a minimum 2-year follow-up were included. Six-week postoperative standing radiographs were used to calculate the GAP score, classified into a spinopelvic state as proportioned (P), moderately disproportioned (MD), or severely disproportioned (SD). A chi-square analysis, receiver operating characteristic curve, and Cochran-Armitage analysis were performed to assess the relationship between the GAP score and mechanical complications. RESULTS:Sixty-seven patients with a mean age of 52.5 years (range 18-75 years) and a mean follow-up of 2.04 years were included. Patients with < 2 years of follow-up were included only if they had an early mechanical complication. Twenty of 67 patients (29.8%) had a mechanical complication. The spinopelvic state breakdown was as follows: P group, 21/67 (31.3%); MD group, 23/67 (34.3%); and SD group, 23/67 (34.3%). Mechanical complication rates were not significantly different among all groups: P group, 19.0%; MD group, 30.3%; and SD group, 39.1% (χ2 = 1.70, p = 0.19). The rates of mechanical complications between the MD and SD groups (30.4% and 39.1%) were less than those observed in the original GAP study (MD group 36.4%-57.1% and SD group 72.7%-100%). Within the P group, the rates in this study were higher than in the original study (19.0% vs 4.0%, respectively). CONCLUSIONS:The authors found no statistically significant difference in the rate of mechanical complications between the P, MD, and SD groups. The current validation study revealed poor generalizability toward the authors' patient population.

Carotid artery stenting (CAS) is an established treatment for patients at high-risk for endarterectomy. Patients who undergo CAS have been shown to have periprocedural microembolic events on transcranial Doppler ultrasonography. Flow reversal is often applied in these situations to prevent distal emboli and concurrently allow blood to flush into the common carotid artery. Patients who demonstrate soft plaque morphology that may embolize distally during CAS benefit from flow reversal. Even so, the all-stroke risk in these patients is nearly 1.4%. High-risk patients typically have more difficult plaque morphology; flow reversal decreases the rate of distal emboli but does not offer the intraprocedural visualization seen with intravascular ultrasound (IVUS). In this paper, we illustrate potential periprocedural outcomes associated with stenting of the stenotic carotid bifurcation under flow reversal and how IVUS influenced endovascular management. Three high-risk patients who underwent CAS with direct common carotid artery cutdown approaches due to common carotid ostia disease with flow-reversal proximal embolic protection also had intraprocedural IVUS performed to evaluate plaque morphology and stability before the protection system was removed. Case 1 illustrates no intraluminal thrombus on IVUS, requiring no further intervention after stent placement. Case 2 demonstrates intraluminal thrombus on IVUS requiring a second stent to stabilize plaque. Case 3 shows the inadequate resolution of thrombus after a second stent, which was addressed with balloon angioplasty. In our experience, using IVUS as an adjunct to CAS under proximal embolic protection helped demonstrate plaque morphology and plaque fragmentation after stent placement. These cases illustrate the potential benefit of allowing stabilization of the plaque before flow reversal is stopped.

BACKGROUND:Various studies have suggested that age ≥80 years is associated with a higher rate of complications after carotid artery stenting (CAS). The Buffalo Risk Assessment Scale (BRASS) predicts complications in symptomatic patients undergoing CAS. Application of the BRASS has shown the ability to improve patient selection. We used the BRASS system to evaluate whether the higher rate of complications associated with CAS in the elderly is related to vascular anatomy. METHODS:A retrospective review of CAS was performed at our institution over 7 years. Demographic information, anatomic characteristics, BRASS categorization, and outcome measures were compared between elderly (≥80 years) and younger patients (<80 years). RESULTS:The study included 447 patients: 335 patients (75%) <80 years and 112 patients (25%) ≥80 years. There were significantly more elderly patients in the high-risk BRASS category (P < 0.01), and more young patients in the low-risk BRASS category (P = 0.04). The complication rates in the 2 groups were similar. Older patients were more likely to harbor complex vascular anatomy: they had significantly higher rates of types II and III aortic arches (P = 0.01 and P < 0.01, respectively), higher percentage of tortuous carotid vessels (P < 0.01), and higher rates of hostile anatomy for deployment of distal embolic protection devices (P = 0.02). CONCLUSIONS:Complex vascular anatomy, rather than age, is the key factor behind the higher CAS-associated complication rate in the elderly. Complications can be avoided through proper patient selection and stratifying patients based on anatomic characteristics, which can be achieved through the BRASS scoring system.

BACKGROUND:Spinal aneurysms are rare causes of spontaneous subarachnoid hemorrhage. METHODS:We present an unusual, initially occult, case of an upper thoracic intradural extramedullary isolated aneurysm arising from the T2 intercostal-radicular circulation that was initially angiographically occult but was discovered due to unique, albeit nonspecific, magnetic resonance imaging findings of spinal cord T2 hyperintensity and contrast enhancement that were noted to progress with a clinical picture of ictal rehemorrhage. RESULTS:Repeat spinal angiography revealed a spinal aneurysm that was treated surgically. CONCLUSION:In cases of sufficient clinical suspicion and nonspecific imaging findings, continued vigilance is advised in seeking an underlying pathoanatomic etiology.

Dysembryoplastic neuroepithelial tumors (DNETs) are low-grade neuroglial tumors that are traditionally considered to be benign hamartoma-like mass lesions. Malignant transformation and disease progression have been reported in complex DNETs. We report a case of a simple DNET with disease progression following subtotal resection. A 34-year-old woman underwent craniotomy with subtotal resection of a large nonenhancing right temporal lobe and insular mass. Histopathological analysis revealed a simple DNET. Magnetic resonance imaging obtained 6 months after surgery demonstrated disease progression with no enhancement or change in signal characteristics. Following concurrent therapy with temozolomide and external beam radiation therapy, a significant radiologic response was observed. Progressive DNET with malignant transformation exhibits predominantly glial transformation and occurs predominantly in complex DNETs. The histological classification of DNETs into simple, complex, and nonspecific are reviewed. Contrast-enhancing regions are more frequently seen in complex tumors, with nonenhancing regions having fewer complex histologic features. Close clinical and radiographic follow-up is important in all cases of DNET. Following tumor progression, radiation therapy with concurrent and adjuvant temozolomide chemotherapy may be an effective treatment.

PURPOSE/OBJECTIVE:Thoracic pedicle screws provide superior curve correction to hook and wire constructs in adolescent idiopathic scoliosis, while increasing cost. The number of implants required for best correction and outcome has not yet been determined. METHODS:We retrospectively reviewed pre- and post-operative radiographs and self-reported outcome measures in an age- and curve-matched cohort of 40 patients with Lenke I AIS who underwent selective fusions between T3/4 and L1. Twenty patients were treated with thoracic pedicle screws at every level bilaterally (CON) and 20 patients with screws at every level on the concave side and skipped levels on the convex side of the curve (SKP). All patients had a minimum 2-year follow-up. Radiographs were assessed for coronal and sagittal curvatures, as well as thoracic torsion and vertebral rotation. Health-related quality of life was assessed using the SRS-22 instrument. Instrumentation cost data were collected for each case. RESULTS:Postoperative follow-up averaged 28 months for the CON group and 29 months for the SKP group. No statistically significant differences were found between groups with respect to age and pre- and post-operative radiographic parameters. Both constructs provided acceptable correction of the main thoracic curves (66.9 vs. 66.6 %, CON group and SKP group, respectively; p = 0.92), and spontaneous correction of the proximal thoracic (41.5 vs. 41.1 %; p = 0.92) and thoracolumbar/lumbar curves (54.8 vs. 54.3 %; p = 0.92). No significant difference was found in postoperative SRS-22 scores (96 vs. 94.3; p = 0.34). The CON group cost for instrumentation was significantly higher than the SKP group ($19,500 vs. $13,300; p = 0.002). There was no statistically significant difference in operating room times between groups. CONCLUSION/CONCLUSIONS:Both construct types provide excellent coronal correction and sagittal balance, with no significant differences in radiographic findings or clinical outcomes. A significant decrease in cost was found with use of skipped screw constructs.

OBJECT Vertebral fractures are the most common osteoporotic fracture. Bone density testing and medical treatment with bisphosphonates or parathormone are recommended for all patients with an osteoporotic fracture diagnosis. Inadequate testing and treatment of patients presenting with low-impact fractures have been reported in various specialties. Similar data are not available from academic neurosurgery groups. The authors assessed compliance with treatment and testing of osteoporosis in patients with vertebral compression fractures evaluated by the authors' academic neurosurgery service, and patient variable and health-systems factors associated with improved compliance. METHODS Data for patients who underwent percutaneous kyphoplasty for compression fractures was retrospectively collected. Diagnostic and medical interventions were tabulated. Pre-, intra-, and posthospital factors that had been theorized to affect the compliance of patients with osteoporosis-related therapies were tabulated and statistically analyzed. RESULTS Less than 50% of patients with kyphoplasty received such therapies. Age was not found to correlate with other variables. Referral from a specialist rather than a primary care physician was associated with a higher rate of bone density screening, as well as vitamin D and calcium therapy, but not bisphosphonate/parathormone therapy. Patients who underwent preoperative evaluation by their primary care physician were significantly more likely to receive bisphosphonates compared with those only evaluated by a hospitalist. Patients with unprovoked fractures were more likely to undergo multiple surgeries compared with those with minor trauma. CONCLUSIONS These results suggest poor compliance with current standard of care for medical therapies in patients with osteoporotic compression fractures undergoing kyphoplasty under the care of an academic neurosurgery service.